Mineralpedia Details for Frondelite
Frondelite
Named for Dr. Clifford Frondel, an American mineralogist and Professor of Mineralogy at Harvard University in Massachusetts, USA. Frondelite is an uncommon mineral that occurs in localities in Brazil, the United States including here in the Black Hills of South Dakota at the Tip Top mine, among others, Germany, Rwanda, and the Democratic Republic of the Congo. It occurs as a product of the alteration of phosphates in granite pegmatites.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/frondelite.pdf
- Formula
- Mn2+Fe3+4(PO4)3(OH)5
- Crystal System
- Orthorhombic
- Cleavage
- Perfect, Distinct, Distinct
- Luster
- Vitreous - Dull
- Color
- brown, brown green, brownish black, green black, dark green
- Streak
- brownish gray
- Class
- Orthorhombic - Dipyramidal
- Fracture
- Brittle - Uneven
- Hardness
- 4.5
- WebMineral
- View Frondelite
- Mindat
- View Frondelite
Frondelite from Galiléia, Doce Valley, Minas Gerais, Brazil
Banded and concentric golden brown, tightly compact, radial, acicular crystals of Frondelite. The bands more than likely represent phases btween Rockbridgeite and Frondelite.
Click thumbnail images for larger view.
